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International audience; Although the problem of computing frequent queries in relational databases is known to be intractable, it has been argued in our previous work that using functional and inclusion dependencies, computing frequent conjunctive queries becomes feasible for databases operating over a star schema. However, the implementation considered in this previous work showed severe limitations for large fact tables. The main contribution of this paper is to overcome these limitations using appropriate auxiliary tables. We thus introduce a novel algorithm, called Frequent Query Finder (FQF), and we report on experiments showing that our algorithm allows for an effective and efficient computation of frequent queries.

International audience; Deterministic networking allows carrying data flows with low data-loss rates and with bounded latency. A typical use-case is the convergence of Operational Technology (OT) with Information Technology (IT), also known as the Industrial Internet. Wireless networks operate on a shared communication medium where the potential external interference along with multi-path fading impact data packet delivery. Since the medium is shared, it is not necessarily possible to employ wired techniques, such as preemption, to guarantee timely delivery. By employing diversity in the time, frequency and spatial domains, wireless technologies with scheduled transmissions, such as IEEE 802.15.4 Time Slot Channel Hopping (TSCH), can mitigate those effects and provide Reliable and Available Wireless communications that approach determinism. Nevertheless, a radio link operating in the ISM band, such as IEEE 802.15.4-TSCH, still needs to handle collisions and possibly re-transmission. Therefore, a single link cannot reliably ensure delivery at all times within bounded latency. It takes redundant links and paths to provide both the high availability and the near consistent reliability that industrial applications require. In this paper, we present the Packet Automatic Repeat reQuest (ARQ), Replication and Elimination (RE), and Overhearing (PAREO) functions to further increase the Quality of Service (QoS) in industrial networks, even when implemented on top of best-effort traffic in a shared network.

International audience

The development of electron cyclotron resonance ion source (ECRIS) at LPSC Grenoble (previously ISN) covers a wide range of applications. Micro-PHOENIX is a compact source whose magnetic confinement is fully generated by permanent magnets. The extraction geometry has been specially designed to manage high currents with a double electrode extraction system to improve the beam characteristics at high voltage. The ECRIS can accept a microwave power frequency from 10 to 18 GHz. It has been installed as a universal injector on the new charge breeder test bench in order to perform the widest range of experiments including mono- or multicharged ion injections. To characterize the analyzed extracted beam, a new emittance meter based on electrostatic deflection plates has been set up and permits one to obtain online high resolution measurements. The first objective of the experiments was to fulfill the future SPIRAL II requirements. After a technical description of the Micro-PHOENIX ECRIS and its beam analysis sys...

We present preliminary results on a study of the 2--850 micron SEDs of a sample of 30 FIRBACK galaxies selected at 170 micron. These sources are representative of the brightest ~10% of the Cosmic Infrared Background. They are a mixture of mostly local (z<~0.3) starforming galaxies, and a tail of ULIGs that extend up to z~1, and are likely to be a similar population to faint SCUBA sources. We use archival Spitzer IRAC and MIPS data to extend the spectral coverage to the mid-IR regime, resulting in an unprecended (for this redshift range) census of their infrared SEDs. This allows us to study in far greater detail this important population linking the near-IR stellar emission with PAH and thermal dust emission. We do this using a Markov Chain Monte Carlo method, which easily allows for the inclusion of ~6 free parameters, as well as an estimate of parameter uncertainties and correlations. Comment: 5 pages, 3 figures. Proceeding for the conference "Starbursts: From 30 Doradus to Lyman Break Galaxies", held in Cambridge (UK) in September, 2004

International audience

International audience

Synopsis The interstellar medium contains both polycyclic aromatic hydrocarbons and cosmic rays. The frontal impact of a single heavy cosmic ray strips out many electrons. The highly charged species then relax by multi-fragmentation, potentially feeding the interstellar medium with hydrocarbon chains. We model both ionization(s) and fragmentation processes and compute the fragments production rates of particular interest for astrophysical models.